Heat exchanger devices for fluid flows

ABSTRACT

Apparatus for producing the transfer of heat from one gaseous flow to another by the alternating and successive passage of the flows through successive sections of an exchanger block having a relatively large specific area comprising a device for dividing the gaseous flows into a plurality of streams flowing in separate passages, the exchanger block of cylindrical configuration being disposed across the passages so as to discontinue same and receive the flows therethrough; a mechanism for imparting an axial reciprocating motion to the exchanger block together with a movement of rotation about its axis; the passages having equal widths and being flat and disposed in parallel relationship, with seals similar to piston-rings disposed between the passages and the block, the sections of the exchanger block consisting of porous elements permitting the fluid flow in the transverse direction but not in the axial direction. This apparatus is particularly adequate for gas turbine equipping land vehicles, notably in that the heat exchanger can be disposed above the longitudinal side members of the chassis.

United States Patent H91 Brille 1 HEAT EXCHANGER DEVICES FOR FLUID FLOWS[75] Inventor: Maurice G. Brille, Suresnes. France [73] Assignee:Societe Anonyme de Vehicules lndustriels et d'Equipements MecaniquesSaviem, Suresnes. France [22] Filed: Feb. 8, 1972 [211 App]. No.:224,580

1 1 July 15, 1975 Primary Examiner-Albert W. Davis, Jr. Attorney, Agent,or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT Apparatus forproducing the transfer of heat from one gaseous flow to another by thealternating and successive passage of the flows through successivesections of an exchanger block having a relatively large specific areacomprising a device for dividing the gaseous flows into a plurality ofstreams flowing in separate passages, the exchanger block of cylindricalconfiguration being disposed across the passages so as to discontinuesame and receive the flows therethrough; a mechanism for imparting anaxial reciprocating motion to the exchanger block together with amovement of rotation about its axis; the passages having equal widthsand being flat and disposed in parallel relation ship, with sealssimilar to piston-rings disposed between the passages and the block, thesections of the exchanger block consisting of porous elements permittingthe fluid flow in the transverse direction but not in the axialdirection. This apparatus is particularly adequate for gas turbineequipping land vehicles, notably in that the heat exchanger can bedisposed above the longitudinal side members of the chassis.

12 Claims, 21 Drawing Figures mrmmu b 15 I915 SHEET PATEHTEML 15 msSHEET HEAT EXCHANGER DEVICES FOR FLUID FLOWS The present inventionrelates in general to means for producing a transfer of heat betweengaseous fluid streams, and more particularly to a heat exchanger to beinterposed between gaseous fluids, notably supercharging compressed airand exhaust gas of engines, such as gas turbine regenerators-exchangers.

The term regenerator-exchanger designates in general heat transferdevices comprising a block of metallic or ceramic permeable material,against which the hot gases and the compressed air are caused to impingeor flow by turns, in order to cool said gases and heat or re-heat saidcompressed air.

In most instances it is the porous block that is shifted from the hotgas stream to the compressed air stream, and vice versa.

Heat exchangers of this character consist as a rule of disks rotating ata relatively low speed. However, any communication between the burntgases on the one hand and the compressed air on the other hand, i.e.,between the conduits in which these gaseous fluids are conveyed, must becarefully avoided, since said compressed air circulates under a pressureof the order of 4 to 5 bars (58 to 73 psi) and even a small loss ofcompressed air by leakage would reduce considerably the turbineefficiency. Therefore, a reliable fluid-tight joint must be providedalong the two lines defining the boundaries between the exhaust gasconduit and the compressed air conduit, which are in actual contact withsaid rotary disk.

However, it is well known in the art that this joint is extremelydifficult to obtain, notably at the points of connection between saidlines and between said lines and the outer periphery of the disk.

it is the essential object of the present invention to provide a heatexchanger in which the abovementioned inconveniences are safely avoided.In the heat exchanger according to this invention the gaseous fluids aredistributed in the form of a sequence of flat parallel jets or streamsof substantially equal width in which the hot and cold jets alternate.This jet assembly is discontinued by a cylindrical space extendingtherethrough and receiving in proper fitting relationship a heatexchanger also of cylindrical configuration to which an axialreciprocating motion is imparted with an amplitude equal to the width ofone of said jets, the gaseou-s flows passing through said cylindricalexchanger along planes perpendicular to its axis, between a stacking ofcellular plates constituting a porous pattern fluidproof in the axialdirection, and according to the present invention a movement of rotationcombined with said axial reciprocating motion is imparted to saidmovable exchanger body.

Thus, in the specific case of a regenerator-exchanger for a gas turbinea block of porous material shifted alternatively from the hot gases tothe compressed air, and vice versa, will be used, thus avoiding therotary disk solution and therefore the joint difficulty by which it isattended, in order to substitute a series of circular packings of thepiston-ring type, i.e., elements operating nowadays with zero orsubstantially zero leakage, for the aforesaid linear joint.

To this end, the gas and air streams are each divided into a pluralityof flat layers disposed alternately, i.e., with one gas layeralternating with an air layer. The cylindrical movable block of the heatexchanger is reciprocated along a rectilinear path by using suitablemeans, so that the section thereof which lies across the gaseous jet isshifted to a position in which it lies across the air jet, and viceversa.

As already mentioned hereinabove a cylindrical block of permeablematerial is used and the joints provided between the hot gas conduit andthe compressed air conduit consist of cylindrical rings. Of course, thisblock of permeable material is so constructed that the fluids can flowonly in the radial direction, not in the axial direction, therethrough.This block may consist of metal and more particularly of metal circularplates stacked to prevent any axial communication and separated from oneanother by projections, corrugations or peaks imparting a highpermeability in any radial direction while creating a turbulenceparticularly favorable to heat exchanges. The reciprocating motion maybe imparted to the cylindrical block either through a crank andconnecting-rod mechanism or through a gaseous pressure (for example thepressure of the compressed air) exerted by turns to each end of theblock, the air consumption in this case being extremely low incomparison with the turbine output.

The fluid tightness between the walls of the jets and the exchanger isobtained very simply by using circular packings of the piston-ring type,as commonly used in internal combustion engines. These rings are fittedinto the wall of the fluid passage and their width is sufficient tocover simultaneously a plurality of cellular plate thicknesses of theexchanger cylinder, so as to constitute therewith a labyrinth-type seal.On the partition side the fluid-tightness or seal is of the valve orautoclave type.

in a typical form of embodiment suggested by way of example these ringsmay be 5 to 6 mm in width, the cell width being of the order of 0.5 mm,with a reciprocation frequency of less than 10 per minute.

in a modified form of embodiment the rings may consist of two concentriclayers of materials having different coefficients of thermal expansion,the material having the higher coefficient being disposed inside theother. With this arrangement, the close-fitted ring tends to seize upwhen cold and to open out during a temperature increment and thereforewhen the pressure increases, thus balancing the gas pressure forcesapplied to these rings and limiting the loss of power due to the dryfrictional contact between the rings and the edges of the cellular metalsheets or plates of the exchanger cylinder. In fact, at the same timethe pressure developed by the compressed air is effective from theexterior of these rings and tends to compress the rings on the block,these two antagonistic actions of temperature and pressure are properlyutilized to cause a positive yet moderate pressure to be eventuallyexerted on the block, to avoid any premature wear and tear of said ringsand also of the block in which they are fitted. This twofold actionremains constantly nearly proportional, for in the specific case of agas turbine the exhaust gas temperature is constantly closely connectedto the pressure of the compressed air blown therein.

According to a specific feature characterizing this invention themovement of rotation of the exchanger cylinder about its axis is addedto its reciprocating motion. This rotational movement promotes thetemperature compensation and therefore the stress in the exchangercylinder, thus improving the homogeneousness of the exchange action.Preferably, the peripheral linear velocity of rotation is selected to behigher than the linear velocity of the movement of translation.

Under these conditions, the cellular pattern is not a purely directionalone. it may consist of a plurality of circular projections having theiraxes parallel to the exchanger axis and interconnecting the walls of apair of adjacent plates of the cellular pattern. Thus, any preferentialorientation is precluded and a turbulent yet continuous gaseous flow isobtained. This rotation is particularly advantageous in that it tends toequalize the block temperature and avoid distortions. The movement ofrotation may be produced independently of the movement of translation,the former being advantageously faster than the latter.

According to a more specific feature characterizing this invention themovements of rotation and translation of the exchanger block areproduced simulta' neously from the action of at least one of the fluidsflowing therethrough.

By controlling the rotational and translational movements of thecylinder by means of a fluid under pressure the exchanger block can beconstructed as a fully self-contained unit as far as the sustainedmovement thereof is concerned, without resorting to cumbersome andexpensive additional mechanisms, a particularly advantageous feature inthe case of gas turbine driven land vehicles.

To this end, according to a preferred form of embodiment, thecylindrical exchanger block is mounted for rotation about its axis andthe axial planes of the gaseous flow passages are off-set on a same sidein relation to said axis.

This asymmetric flow the gases through the exchanger causes the latterto rotate as in the case of a turbine rotor, the loss of pressure in itscellular stacking providing the necessary reaction.

Thus, the passages may be designed with a lateral wall directedtangentially to the exchanger block, the other wall lying approximatelyin the diametral plane of said block.

This other wall may lead directly to the exchanger or, according to amodification adapted to improve the output, it may be outflared so as tobe connected tangentially thereto.

The outlet passages are designed symmetrically to the correspondinginlet passages, in relation to an axial plane of the exchanger block.

This arrangement is also characterized by a considerable flexibility inthe orientation of the fluid jets or passages, this constituting avaluable feature in the case of an adaptation to existing vehicles.

The rotational racing of the exchanger block is prevented by the brakingaction exerted by the sealing rings.

This undesired racing would occur if the rings, when at a relativelyhigh temperature, expanded to a degree reducing to an abnormally lowvalue their frictional contact with the cylindrical surface of theexchanger block. This expansion is balanced by the higher gas pressurein the case of high rotational speed of the turbine, this pressuretending to re-close the rings by valve effect. The higher rotationalspeed of the exchanger increases the velocity of flow of the gases onthe ring surface and therefore the rate of heat transfer, thus tendingto cool said rings and to contract them, so as to retard the blockrotation.

Conversely, when the exchanger block is retarded or even brought to astandstill the gas mixing action produced about the rings is decreasedand at the same time their rapid heating by conduction as a consequenceof the contact with the exchanger surface is attendedby the re-openingof said rings. 7

When the reciprocating motion is obtained by utilizing the gaseouspressure of one of the fluids circulating through the exchanger, forexample compressed air in the case of an air-gas exchanger of a gasturbine, directed by turns against each end face of the exchanger block,the latter being thus caused'to abut against stop means with itsopposite face, this movement is almost instantaneous for the pressure iseffective throughout the area of the exchanger face. In order properlyto control the temperature increment time of the exchanger blocksections, the frequency of the changes of position of said block isadjusted by means of a proper time lag introduced into theoperation ofthe reversing valve controlling the pressurization of one face and atthe same time the release of the other face by venting same to the freeatmosphere.

To this end, a reversing valve responsive to an electrical time-lagdevice may be used, of a type currently used in the field of pneumaticcontrol systems, but a valve incorporating pneumatic retarding means,usually more cumbersome but operating without any external source ofpower, may also be used.

Thus, according to this invention, the pressure of the fluidscirculating through the exchanger is utilized for advantageously andadjustably obtaining the combined alternate movements of translation androtational movements of the exchanger block. This arrangement isparticularly advantageous in the specific case of gas turbine drivenland vehicles due to its simplicity and moderate weight and over-alldimensions, and also to its flexibility of mounting and orientation,notably in the case of trucks.

Another essential advantageous feature characterizing this invention isthat it facilitates considerably the general design of a gas turbine inthe case of a vehicle. in fact, in known heat-exchangers the disks aredisposed coercively on the sides of the turbine, so that the transverseover-all dimensions, in. the plane of the turbine shaft becomerelatively large and are difficult to house between the two longitudinalbeams of the chassis. Usually, in order to keep this width withinreasonable reduced limits, the fluid passages are constructed withshapes less satisfactory from the point of view of pressure losses. Withthe exchangers according to this invention these can be disposed abovethe turbine axis and behind the turbine unit, so that the transverseoverall dimensions across the longitudinal members of the vehicle remainwithin reasonable limits. With the exchangers of this invention it isalso possible to use particularly direct exhaust pipes, without anypressure loss except for the flow through said blocks.

Another valuable feature of this arrangement lies in the possibility ofdirecting indifferently and cross the gaseous flows, thus facilitatingand permitting the arrangement of the exchanger or exchangers under thebest possible conditions in the room available. Furthermore, at leasttwo exchanger cylinders are mounted symmetrically, as a rule, inparallel, with inverted displacement off-settings and the capacity forproducing a constant exchange rate.

The heat exchangers according to this invention are also advantageous inthat the exchanger cylinders can be removed and replaced very easily forchecking and cleaning purposes, by pulling them from one end, like thecartridges of filter units, thus minimizing maintenance costs.

A complete understanding of the invention may be obtained from theforegoing and following description thereof taken together with thedrawings in which:

FIG. 1 is a front elevational view of a disk exchanger of a known type;

FIG. 2 is a sectional view of the same disk, taken along a diametralplane;

FIG. 3 is an axial section of a heat exchanger according to thisinvention;

FIG. 4 is a cross sectional view of the exchanger of FIG. 3;

FIG. 5 is a section similar to FIG. 3 in the ,case of a gaseous pressuremotion control system (utilizing for example compressed air);

FIG. 6 is a plan view of a sealing ring;

FIG. 7 is an elevational view of the ring of FIG. 6;

FIG. 8 is a sectional view of a typical ring fitted in position;

FIG. 9 is a sectional view of a composite ring consisting of abimetallic structure;

FIGS. 10 and 11 corresponding to FIGS. 3 and 5 respectively illustrate adevice for rotatably driving the exchanger cylinder;

FIG. 12 is a modified form of embodiment of the structure shown in FIG.4, wherein the gaseous flows have different directions;

FIG. 13 is a perspective view of a block die for illustratingdiagrammatically the multidirectional exchange and turbulence reliefelements;

FIG. 14 is a diagrammatic axial section showing a general view of aturbine for equipping a vehicle;

FIG. 15 is a corresponding plane view of an advantageous arrangement fora similar assembly;

FIG. 16 illustrates a plan view from above, in the direction of the axisof the heat exchanger, showing diagrammatically an exchanger block andthe means for connecting the fluid passages thereto;

FIG. 17 is a modified form of embodiment of said fluid passages;

FIG. 18 is a diagrammatic axial view of a vehicle turbine assembly,similar to the view of FIG. 14;

FIGS. 18A and 188 show, more specifically, apparatus which may be usedin the apparatus of FIG. 18, and

FIG. 19 is a plan view from above taken along the lines XIXXIX of FIG.18.

Referring first to FIGS. 1 and 2 illustrating a known type of heatexchanger, wherein the disks revolve slowly and intersect simultaneouslythe cold and hot flows, the two radii separating the two passages andalong which it is desired to provide a sealed or fluidtight joint, areclearly shown together with the special rollers for rotatably drivingsaid disks through peripheral teeth, and the particularly elaborate andcontorted configuration of the passages or duct means.

FIG. 3 shows in elevation an exchanger constructed according to theprinciple of this invention, which comprises a compressed air inlet 1,an exhaust gas inlet 2, the division of the inlet duct 1 into aplurality of branch sections 3, the number of these branch sectionsbeing if desired greater than two, and also the division of inlet duct 2into a plurality of branch sections 4 interposed between said sections3. The cylindrical exchanger block 5 extends at right angles through allthese branch sections which on the other hand have all the same widthcorresponding to the block stroke. The joint between the block and theduct sections is sealed by means of rings 6 illustrated more in detailin FIGS. 6, 7, 8 and 9. These sealing rings are substantially likeordinary piston rings, with a cut gap at mid-height as shown at 7. Thecompressed air pressure penetrates as usual into the ring groove 8 andurges the ring against the cylinder at 9. As already explainedhereinabove, this ring may consist of a bimetallic assembly with thematerial or strip having the higher coefficient of expansion disposedinside. These two strips may have a constant thickness, or, asillustrated in FIG. 9, a variable thickness to take due account of thehigher temperature on the burnt gas side 13 than on the compressed airside 14. In this case the interface of these two strips is oblique, asshown at 12. Thus, by suitably selecting the materials and dimensions ofthe bimetallic strip, it is possible to adjust very accurately theopening thereof. A slight rounding of the edges of the friction face ofthese rings will facilitate the engagement and frictional contact withthe edges of the exchanger sections during the operation.

The block comprises a series of circular stamped or pressed plates orlike elements 21 stacked and clamped on a central rod 15 by means ofendflanges l6 and nuts 17. The extensions of this rod 15 are guided insliding elements and at the upper end the rod is driven through aconnecting-rod l9 and a crank 20. The circular plates 21 may consist ofdisks formed with projections 22 or peaks 23 (FIG. 13) so that ducts 3and 4 are not coer cively directed through the block in mutual parallelrelationship as illustrated in FIG. 4, and may form be tween each otheran angle as shown in FIG. 12. Since the block is reciprocated in theaxial direction through a distance equal to the width of ducts 3 and 4,the heat stored in the materials is transferred into the next lower orupper cold duct.

The movements of block 5 may be obtained by means of compressed airpressure. In FIG. 5 the same block as described in the foregoing isillustrated but without any extension of the central rod and without anyguide means, the compressed air being supplied for example through ducts24 either to the upper portion or to the lower portion by a valve 25automatically controlled by pneumatic time-lag means 55. The used airescapes through nozzle means 26. The movement thus obtained isrelatively rapid and the block remains a certain time in each endposition, the movement being damped out however by a proper control ofthe air exhaust across the nozzle means 26. In this case the block isretained only by its sealing rings, without any additional stress.

However, if a movement of translation alone is obtained a certainasymmetry may result in the heat transfer action and also in thecorresponding expansions. Therefore, the present invention is directedmore particularly to a rotary block of the type illustrateddiagrammatically in FIGS. I0 and 11. It will be seen that the rod 15 mayhave a ring shaped extension 27 solid with a gear 28 driven in turn froma pinion 29. The translation is still obtained either through the bead30 and the connecting-rod and crank mechanism 19, 20, or throughcompressed air supplied via ducts 24.

It may be noted that the rotation of the aforesaid block comprising thestamped or pressed metal plates 23 is favorable not only to thetemperature balance but also to turbulence about the peaks and thereforeto the heat exchange effect. The term peak is used herein to denote anytype of round shaped projection producing the same resistance to thegaseous fluid flow in all directions.

Under these conditions it is nearly certain that the exchange rate andregularity are greater than in the form of embodiment comprising asingle rotary disk. Therefore, it should be possible, theoretically, tomove the block at a higher speed and thus improve its heat transfercapacity, but this speed is limited by the unavoidable air/gas mixingduring the axial movements of the block. Similarly, the cross-sectionalarea of the inlet ducts 3 and 4 could be increased, but a correspondingincrement in the number of rings would result. An optimum choice of thedimensions must be made as a function of the specific and desiredperformances of this heat exchanger.

It may also be noted that the block rotation is combined with itstranslation for producing a tacking" movement propitious to thereduction in the coefficient of friction on the block and therefore tothe reduction in the mechanical losses and to a longer useful life ofthe apparatus, even in the case of a ceramic block. In fact, no detailshave been proposed herein for a possible constitution of a ceramicblock, the ideal solution consisting in reproducing as closely aspossible what is obtained with the metal elements 23. The plates formedwith the aforesaid peaks or like projections may also be made ofceramic. It is also possible to construct a unitary or one-piece ceramicblock, provided of course that no axial communication or circulationtakes place.

The arrangement may be fitted in a turbine as illustrated in FIGS. 14and 15 illustrating a typical example of a possible application of theseheat exchangers.

The supercharger 31 is driven from the first turbine wheel 32. Withinthe gaseous flow in said duct the second turbine wheel 33 drives thereduction gearing 34 and the output shaft 35. Between the first andsecond wheels 32, 33 a swivelling distributor 36 is provided. The aircompressed by supercharger 31 is divided into two streams by thesymmetric manifolds or header 37. Each manifold or header 37 terminatesin front of the vertical cylindrical exchanger 38 and is divided ofcourse as shown in FIGS. 5 and 11. They open into a general manifold orheader 39 supplying air to the combustion chamber 40. The primary airnecessary for the combustion penetrates at 41 and the secondary air at42, the stream of burnt or exhaust gas being guided through the manifold43 directing the hot gases under pressure towards the turbine 32. Thegases expanding at the outlet of turbine 33 are directed to the rearthrough duct means 44 also extending through the heat exchangers 38after having been divided into a plurality of channels as illustrated inFIGS. 3, 5 and 11, but without changing their direction, exceptdownstream of the turbine at which a single elbow 45 directs them backto the chimney 46.

The means for controlling the movements of exchangers 38 are not shownbut the means contemplated in FIGS. 3, 5, l0 and 11 may be used to thisend. It may be noted that the exchangers 38 are disposed completelybeneath the axis 47 of the turbine unit, i.e.,

above the lognitudinal side members of the vehicle chassis, so thatthese longitudinal side beams may be disposed in the position shown indash lines at 48.

The two exchangers must be synchronized and off-set by a half-stroke inorder to improve the regularity of the air temperature.

With this arrangement the clogging of the heat exchanger with soot takesan extremely long time and even when it occurs it is clear that theblocks of porous material can be disassembled very easily without havingto remove the turbine unit from the vehicle, by simply removing theupper cover and introducing hot gases under pressure for expanding therings 6 and eliminating their frictional contact. This block replacementmay be effected within a few minutes.

According to a preferred form of embodiment, the movements of rotationand translation of the exchanger block are obtained simultaneouslythrough the action of at least one of the pressure fluids flowingtherethrough.

To this end and as illustrated in FIGS. 16 and 17 the axial planes 3,,and 3,, and 4, and 4 of passages 3 and 4 are off-set in relation to theaxis 50 of the exchanger block.

In the form of embodiment illustrated one of the lateral walls of thegaseous flow inlet passage is tangent to the external cylinder of theexchanger block, the other wall being directed in a substantiallydiametral plane of the exchanger block, and on the other hand thegaseous flow discharge passages are symmetrical to the inlet passages inrelation to a diametral plane of the exchanger.

Thus. the exchanger block 5 is rotatably driven about its axis 50 due tothe pressure gas introduced through the passages 3 and 4 and flowingthrough the sections of block 5. These passages are shifted in relationto the axis 50 so that the dynamic effect of the fluids is preponderantover one half of block 5 and generates a torque producing its rotation.The exchange is advantageously located in positions where elbows arenecessary in the general system so that this driving effect can beobtained without resorting to additional means.

FIG. 17 illustrates a modified form of embodiment of this arrangement,wherein the passage is connected through a rounded wall 51 externallytangent to the block 5, thus reducing pressure losses and increasing thepassage output.

FIG. 18 illustrates an arrangement contemplated in the case of a vehicleand similar to that illustrated in FIGS. 14 and 15. It will be seen thatin this modified arrangement a supercharger 31 driven from the firstturbine wheel 32 supplies compressed air to headers 37 having a dividedend portion upstream of the cylindrical exchanger 38, the air emergingtherefrom being directed by the general header 39 into the combustionchamber 40 through ports 41 and 42. The combustion gases are directed byheader 43, 44 to exchanger 38 from which they flow to the chimney 46. Asshown in this figure the axis 50 of the heat exchanger is disposedacross or transversely to the direction of flow of the fluid passages inorder to reduce pressure losses by reducing the length of these passagesand obtaining a flow path as direct as possible.

FIG. 19 illustrates in section the contour of passages 37 and 44 inwhich the gaseous flows impart a torque to the exchanger block 5. Asalready explained in the foregoing the block axis 50 is off-set inrelation to the axial planes of these passages, and the resultingasymmetry of the gaseous flow determines the rotation of said block.

In this example the torque is provided by both hotgas and cold-gasstreams. However, the drive may be derived from one fraction only of thegases flowing through the exchanger, the other fraction flowing throughthe exchanger section without producing any torque or even incounter-current relationship.

With this arrangement it is possible to regulate the driving torqueapplied to the exchanger and to prevent same from racing, in conjunctionwith the ring action as explained hereinabove.

This flow of one fraction of the gases in countercurrent relationshipwhich acts as a dynamic brake retarding the rotation of the exchangerblock is also advantageous in that it increases the velocity of flow ofthese gases along its walls and therefore the rate of heat exchange. Asthe rotatable drive is caused by only one fraction of the gasthroughout, it is less sensitive to variations in this throughput.

The reciprocating movement of translation of the exchanger block is alsocaused by the gas pressure and controlled through the reversing valve 25(FIG. 18) supplied with gas under pressure through a branch line 52connected to one of the fluid passages upstream of the exchanger. Thisgas is distributed by turns to each one of the end faces of thecylindrical exchanger block via ducts 53 and 54, the pipe associatedwith the opposite, non-pressurized face being vented at the same time tothe atmosphere.

The time-lag actuation of reversing valve 25, preset as a function ofthe desired heat exchange time of the block sections is obtained througha time-lag device 55. ln the case of an electric time-lag the latter mayconsist of an electric timing mechanism controlling an electromagnetconnected to valve 25. If a pneumatic time-lag device is used the latteris supplied with pressure fluid through a pipe line 56 connected tomanifold 52. In the use of an electric time lag device a coil 55' of anelectromagnet may be energized by the closure of a circuit through anelectric timing mechanism 55''.

In FIG. 18B is shown a preferred embodiment, wherein use is made of thepressure involved by the gases released from the turbine, thus avoidingenergy expenses. The device comprises a piston 61 located within device55, for controlling valve intended to enable the gases coming from duct52 to flow towards duct 53 and 54. Duct 52 is connected to duct 56 whichcooperates with valve 57 itself connected by means of a rod system tovalve 58, so as to feed in turn a gas flow through ducts 59 and 60 ateach respective face of piston 61. Piston 61 is integral with cross-head62 itself provided with a fork member 63 intended to insure that valve57, and thus valve 25, is reversed in both directions.

Time-lag device 55 comprises at each end thereof calibrated openings 64having a flow area smaller than that of ducts 59 and 60. Gasoverpressure within device 55 causes piston 61 to move towards theopposite extremity, until fork 63 pushes the lever of valve 57 out ofits point of unstable equilibrium, i.e., in the opposite position, thusactuating valve 25 so as to invert the gas flow within duct 53 and 59towards ducts 54 and 60, wherein the aforesaid process is repeated, dueto the pressure increase on the relative face of piston 61.

Of course, various modifications may be applied to the specific forms ofembodiment of the present invention which are shown and describedherein, without departing from the scope of the invention as defined inthe appended claims.

What is claimed as new is:

l. A device for producing a heat exchange between gaseous flows in whichthe heat transfers take place between a hot flow and a cold flow bycausing said flows to be directed by turns and successively throughsections of a heat exchanger block comprising:

a. a plurality of adjacent flat and parallel passages of equal widthinto which said gaseous flows are divided, the passages receiving thegas to be cooled alternating with the passages receiving the gas to beheated, said plurality of passages being associated with and interruptedby a cylindrical space disposed thereacross;

b. a cylindrical exchanger block provided within said cylindrical spaceand being both axially reciprocating and rotatable therein, theamplitude of reciprocation corresponding to the width of one of saidpassages, said block including stacked pressed plates forming a porouscellular structure in the transverse direction but being fluid-tight inthe axial direction of said block so as to provide fluidtightnessbetween said gaseous flow passages and said enchange block, said gaseousflows passing through said block in planes perpendicular to the blockaxis;

c. circular seals in frictional contact with the periph eral surface ofsaid block and fitted in the walls of said plurality of passages toprovide said fluidtightness;

d. means for axially reciprocating said exchanger block, saidreciprocating means including the flow of at least one of said gasesflowing through said block; and

e. means for continously rotating said exchanger block, said rotatingmeans including the flow of at least one of said gases flowing throughsaid block.

2. Heat exchanger device according to claim 1 wherein said means foraxially reciprocating comprises means for alternately supplying one ofsaid gases to an upper and lower portion of said exchanger block.

3. Heat exchanger device according to claim 2 wherein said means foralternately supplying comprises:

a. a first duct connected to the upper portion of said block;

b. a second duct connected to the lower portion of said block; and

c. an automatically controlled valve for directing a supply of the gasto either said first or second duct.

4. Heat exchanger device according to claim 1 wherein the alternatepassages have axial planes that are off-set on a same side in relationto the axis of rotatiori of said block and said rotating means comprisesat least one fraction of said gaseous flow directed across saidexchanger block.

5. Heat exchanger device according to claim 4 wherein one of the lateralwalls of the off-set alternate passages is tangent to said exchangerblock, the other lateral wall being directed in a substantiallydiametral plane of said block.

6. Heat exchanger device according to claim 5 wherein said lateral wallsof said passages lying substantially in a diametral plane of said blockare connected thereto through a rounded portion directed tangentially tothe outer cylindrical surface of said exchanger block.

7. Heat exchanger device according to claim 4 wherein said passages forreceiving the gas to be cooled are disposed symmetrically to thepassages for receiving the gas to be heated in relation to a diametralplane of said exchanger block.

8. Heat exchanger device according to claim 4 wherein one portion of thepassages for receiving the gas to be heated is off-set on a same side inrelation to the axis of said exchanger block and another portion isoff-set on the other side of said axis whereby the difference betweenthe inverted torques applied to said exchanger block causes the rotationthereof.

9. Heat exchanger device according to claim 1 wherein said reciprocatingmeans comprises:

a. means for exposing gas by turns to the end faces of said exchangerblock;

b. a reversing valve means for alternately supplying the flow of gas tothe respective end faces; and

c. time lag means for actuating said reversing valve.

10. Heat exchanger device according to claim 9 wherein said time lagmeans comprises an electromagnetic control device connected to saidreversing valve means and an electric timing mechanism associated withsaid electromagnetic control device.

11. Heat exchanger device according to claim 9 wherein said time lagmeans comprises a pneumatic timing device responsive to one of the gasesflowing through said exchanger block.

12. Heat exchanger device according to claim 9 wherein said reversingvalve means simultaneously supplies gas to one end face of saidexchanger block and vents gas from the other end face to the atmosphere.

1. A device for producing a heat exchange between gaseous flows in whichthe heat transfers take place between a hot flow and a cold flow bycausing said flows to be directed by turns and successively throughsections of a heat exchanger block comprising: a. a plurality ofadjacent flat and parallel passages of equal width into which saidgaseous flows are divided, the passages receiving the gas to be cooledalternating with the passages receiving the gas to be heated, saidplurality of passages being associated with and interrupted by acylindrical space disposed thereacross; b. a cylindrical exchanger blockprovided within said cylindrical space and being both axiallyreciprocating and rotatable therein, the amplitude of reciprocationcorresponding to the width of one of said passages, said block includingstacked pressed plates forming a porous cellular structure in thetransverse direction but being fluid-tight in the axial direction ofsaid block so as to provide fluid-tightness between said gaseous flowpassages and said enchange block, said gaseous flows passing throughsaid block in planes perpendicular to the block axis; c. circular sealsin frictional contact with the peripheral surface of said block andfitted in the walls of said plurality of passages to provide saidfluid-tightness; d. means for axially reciprocating said exchangerblock, said reciprocating means including the flow of at least one ofsaid gases flowing through said block; and e. means for continouslyrotating said exchanger block, said rotating means including the flow ofat least one of said gases flowing through said block.
 2. Heat exchangerdevice according to claim 1 wherein said means for axially reciprocatingcomprises means for alternately supplying one of said gases to an upperand lower portion of said exchanger block.
 3. Heat exchanger deviceaccording to claim 2 wherein said means for alternately supplyingcomprises: a. a first duct connected to the upper portion of said block;b. a second duct connected to the lower portion of said block; and c. anautomatically controlled valve for directing a supply of the gas toeither said first or second duct.
 4. Heat exchanger device according toclaim 1 wherein the alternate passages have axial planes that areoff-set on a same side in relation to the axis of rotation of said blockand said rotating means comprises at least one fraction of said gaseousflow directed across said exchanger block.
 5. Heat exchanger deviceaccording to claim 4 wherein one of the lateral walls of the off-setalternate passages is tangent to said exchanger block, the other lateralwall being directed in a substantially diametral plane of said block. 6.Heat exchanger device according to claim 5 wherein said lateral walls ofsaid passages lying substantially in a diametral plane of said block areconnected thereto through a rounded portion directed tangentially to theouter cylindrical surface of said exchanger block.
 7. Heat exchangerdevice according to claim 4 wherein said passages for receiving the gasto be cooled are disposed symmetrically to the passages for receivingthe gas to be heated in relation to a diametral plane of said exchangerblock.
 8. Heat exchanger device according to claim 4 wherein one portionof the passages for receiving the gas to be heated is off-set on a sameside in relation to the axis of said exchanger block and another portionis off-set on the other side of said axis whereby the difference betweenthe inverted torques applied to said exchanger block causes the rotationthereof.
 9. Heat exchanger device according to claim 1 wherein saidreciprocating means comprises: a. means for exposing gas by turns to theend faces of said exchanger block; b. a reversing valve means foralternately supplying the flow of gas to the respective end faces; andc. time lag means for actuating said reversing valve.
 10. Heat exchangerdevice according to claim 9 wherein said time lag means comprises anelectromagnetic control device connected to said reversing valve meansand an electric timing mechanism associated with said electromagneticcontrol device.
 11. Heat exchanger device according to claim 9 whereinsaid time lag means comprises a pneumatic timing device responsive toone of the gases flowing through said exchanger block.
 12. Heatexchanger device according to claim 9 wherein said reversing valve meanssimultaneously supplies gas to one end face of said exchanger block andvents gas from the other end face to the atmosphere.